The software on the computer included a program that allowed you to look up tele-
phone numbers and dial them from the computer. A handset connected to the back of
the computer then allowed you to use the computer as your phone (perhaps the first
address book?). But the voice itself was still analog and did not go through the data
network. In fact, the data connection was made through the telephone network.
Then as years moved on, digital switching became more prevalent and we began
seeing systems designed to support both voice and data. Of course, voice was always
the primary function of the switches, with the added capability of packet switching.
I remember the first true digital packet switch I worked with was a thing called the
Lexar, built by Lexar Corporation (later to become United Technologies, then Telex,
than Memorex Telex, and then I lost track).
The voice was actually packetized and sent to digital phones, which meant that data
could also be packetized and sent to and from the phones. Computers connected via
a serial connector (remember those?) on the back of the phone at a dizzying speed of
19.2 Kbps. We were getting closer to seeing computers and data combined, but still,
there lacked a network that could bridge all of these systems together.
There were, of course, mainframe computers and dedicated networks running SNA.
I did work on some of these for a while, but they were so inflexible and the SNA
protocol was very limited compared to today’s protocols. The network elements were
pretty basic, operating at the transport layer to route data packets from mainframe
to terminal. These networks were really designed to provide dumb terminals access
to the mainframes, rather than to share data between users.
Then came the Internet, and everything changed. Suddenly we all had access to a
giant public network that allowed us to connect and exchange all types of data with
anyone who had a connection. New Internet service providers (ISPs) began popping up
offering electronic mail and message boards, and later news services and newsgroup
access.
These ISPs continue to grow and offer new services as the Internet matured.
When the World Wide Web (WWW) was introduced, communication was changed
forever. Suddenly we could shop online, establish our own presence on the Internet,
and socialize with people from all over the world.
It was only natural that the next big service would be Voice over IP (VoIP). It is very
fulfilling for me to see these networks finally maturing to where they have become
mainstream after so many decades of experimentation and failed attempts. Today we
can finally enjoy the many features and capabilities that packet networks enable with
telephone service combined with our e-mail and data service.
Yet for many years it was like the Wild Wild West, with many different implementa-
tions and many different configurations to support VoIP networking. There were the
legacy telephony guys trying to make the packet network emulate a switched network,
and the data guys trying to make the packet network support voice.
In the end, we meet in the middle. New protocols have been developed to help make
VoIP more robust and reliable while supporting quality as good as or superior to legacy
networks. We see networks beginning to mature and standardize on their technolo-
gies so that they can interoperate with other networks, and so vendor equipment will
interoperate end to end.
xvi Introduction
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